An SiC (silicon carbide) semiconductor is excellent in dielectric breakdown resistance and heat conductivity, and watched with interest as a semiconductor suitable for application to an inverter or the like of a hybrid car.
For example, an inverter employing an SiC semiconductor has a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). This type of SiC semiconductor device includes an SiC substrate and an N-type SiC epitaxial layer stacked on the SiC substrate. A plurality of P-type body regions (well regions) are formed on a surface layer portion of the SiC epitaxial layer at intervals from one another. An N-type source region is formed on a surface layer portion of each body region at an interval from a peripheral edge of the body region. A gate electrode made of N-type polysilicon (polysilicon doped with an N-type impurity) is formed on the SiC epitaxial layer. The gate electrode is opposed to a region (a channel region) between the peripheral edge of the body region and a peripheral edge of the source region through a gate oxide film. A P+-type body contact region is formed on the inner side of the source region to pass through the source region in the depth direction.
An interlayer dielectric film is formed on the SiC epitaxial layer. The gate electrode is covered with the interlayer dielectric film. A source electrode is formed on the interlayer dielectric film. The source electrode is connected to the source region and the body contact region through a contact hole selectively formed in the interlayer dielectric film.
A voltage exceeding a threshold is applied to the gate electrode in a state where the source electrode is grounded and a positive voltage is applied to a drain electrode formed on the back surface of the SiC substrate, whereby a channel is formed in a portion close to the interface between the body regions and the gate oxide film, and a current flows between the source electrode and the drain electrode.